It’s difficult to answer to question “How much is an average life span of puffer fish”. However, their close relatives freshwater green and leopard tetraodons that contain in aquariums live quite a long time (if kept in the right conditions) 10 – 12 years. Puffer most likely live no less.
They feed on everything they can reach, especially adore mollusks. Again, from the experience of communication with aquarium tetraodones.
Puffer fish in a stressful situation can increase in size. And quite strongly – in 2-3 times. This skill does not depend on the environment – in special bags located in the abdominal cavity, the fish can recruit both water and air. Stay in such a state the fish can, until all around is quiet.
But some of the specimens are dying, bloated, without waiting for improvement. By this behavior the fish justifies its first name. However, the fish that seizes it, too, will die. Simply choking.